namespace mercury {
  export class Person {
    private name: string;
    private birthday: Date;

    constructor(name: string) {
      this.name = name;
    }

    setBirthday(birthday: Date): void {
      this.birthday = birthday;
    }

    print(): void {
      console.log(`hello, ${this.name}! birthday is ${this.birthday}`);
    }
  }
}

let p = new mercury.Person('test');

p.setBirthday(new Date(1983, 3, 26));

p.print();
